1. Field of the Invention
This invention relates to packages for integrated circuits, more especially for very large scale integrated circuits.
2. Description of the Related Art
Such packages essentially comprise an enclosure for housing an integrated circuit and a plurality of leads extending through the enclosure wall, the inner end of each lead being adapted for connection to an integrated circuit housed in the enclosure and the outer end of each lead being adapted for external connection e.g. to a conductor of a printed circuit board. Normally the enclosure is required to be capable of being hermetically sealed after insertion of the integrated circuit in the enclosure and connection of the leads to the integrated circuit.
In a known form of such a package, the leads emerge from the enclosure via a seal between flat surfaces of two parts of ceramic material forming the enclosure. Consequently, when the package is placed on a circuit board the leads are slightly spaced from the board and require to be formed to some extent to facilitate soldering to conductors on the board. This forming operation frequently causes failure of the hermetic seal between the leads and the ceramic parts.
A further problem with such packages is the increasing fragility of the leads with increasing lead density, with a resultant increase in the possibility of damage to or misplacement of, the protruding outer ends of the leads during manipulation of the package for testing purposes and attachment of the package to a circuit board.